lod CORALS AND CORAL LSLANDS. 



space between the cannon. After breaking three inches of 

 coral crust I found the collar-bone of a man, a brass regulating 

 screw belonging to a quadrant, and some large lead bullets. . . . 

 The magazine must be under the branch-coral, which has been 

 sixty-four years growing. ..." 



Here we have a height of sixteen feet in a Madrepora at- 

 tained in sLxty-fou?' years, or at the rate of three inches a year. 

 Madrepores evidently grow with much greater rapidity than 

 the massive corals. 



Observations on the rate of growth of different species 

 might easily be made by those residing in coral seas, either in 

 the manner adopted by Mr. Allan (placing the specimens on 

 a platform which could be raised for examination from time 

 to time — say every five years), or by placing marks upon par- 

 ticular species where they are immovably fixed to the bottom. 

 By inserting slender glass pins a certain distance from the sum- 

 mit of a Madrepore, its growth might be accurately measured 

 from month to month. Two such pins in the surface of an 

 Astrsea would in the same manner, by the enlarging distance 

 between, show the rate of increase in the circumference of 

 the hemisphere ; or if four were placed so as to inclose an 

 larea, and the number of polyps counted, the numerical in- 

 crease of polyps resulting from budding might be ascertained. 

 If specimens are selected, as done by Mr. Allan, it is import- 

 ant that they should be placed where other corals are growing 

 in luxuriance, so as to be sure that there are no deleterious 

 influences to retard growth. It is to be hoped that some of 

 the foreign residents at the Sandwich, Society, Samoan, or 

 Feejee Islands will take this subject in hand. There are also 

 many parts of the West Indies where these investigations 

 might be conveniently made. 



